1. Field of the Invention
This invention relates to a sealing arrangement for a rotor of a turbomachine. More particularly, but not exclusively, the invention relates to a sealing arrangement which can be used in the rotor of a gas turbine.
2. Brief Description of the Related Art
It is a recognised problem that gases can leak from the flow channels formed by component parts, such as blade roots and heat shields, of a rotor in a turbomachine. The effects of such leakage will depend upon the type of turbomachine, but include: unnecessary heating, a loss of strength, mechanical failure, a loss of efficiency and a need for undesirably expensive materials.
It is well known to address the foregoing problems by the use of sealing elements, which often take the form of plates mounted between the component parts. In a typical arrangement, a portion of each plate is inserted into a slot made in the root part of a blade and another portion is inserted into a slot made in an adjacent heat shield.
Whilst such arrangements have been successful in reducing gas leakage, they suffer from a disadvantage that the slots in the adjacent component parts need to be provided at the same radial level and implementation of this precondition requires the component parts to be manufactured to within extremely narrow tolerances. It is further the case that the relative positions of the slots can change during operation of the turbomachine, due to the influences of high temperatures and centrifugal forces, with the effect that a plate can be subject to shear or to fracture.
To compensate for this mutual displacement of the slots, it is known to make the slots sufficiently wider than the thickness of the sealing plates. However, in this case, the plates are positioned in their slots with a significant skew and this results in unsatisfactorily high levels of leakage past the seal. When many joints are provided between individual sealing elements in the circumferential direction, the number of potential leakage paths tends to increase, with the effect that the problem is particularly exacerbated.